Closing yield gaps: perils and possibilities for biodiversity conservation.

Increasing agricultural productivity to 'close yield gaps' creates both perils and possibilities for biodiversity conservation. Yield increases often have negative impacts on species within farmland, but at the same time could potentially make it more feasible to minimize further cropland expansion into natural habitats. We combine global data on yield gaps, projected future production of maize, rice and wheat, the distributions of birds and their estimated sensitivity to changes in crop yields to map where it might be most beneficial for bird conservation to close yield gaps as part of a land-sparing strategy, and where doing so might be most damaging. Closing yield gaps to attainable levels to meet projected demand in 2050 could potentially help spare an area equivalent to that of the Indian subcontinent. Increasing yields this much on existing farmland would inevitably reduce its biodiversity, and therefore we advocate efforts both to constrain further increases in global food demand, and to identify the least harmful ways of increasing yields. The land-sparing potential of closing yield gaps will not be realized without specific mechanisms to link yield increases to habitat protection (and restoration), and therefore we suggest that conservationists, farmers, crop scientists and policy-makers collaborate to explore promising mechanisms.BP was funded by the Zukerman Research Fellowship in Global Food Security at King’s College, Cambridge.This is the accepted manuscript of a paper which was published in the Philosophical Transactions of the Royal Society B: Biological Sciences (B Phalan, R Green, A Balmford, Phil. Trans. R. Soc. B 2014, 369, 20120285

Land sparing to make space for species dependent on natural habitats and high nature value farmland.

Empirical evidence from four continents indicates that human food demand may be best reconciled with biodiversity conservation through sparing natural habitats by boosting agricultural yields. This runs counter to the conservation paradigm of wildlife-friendly farming, which is influential in Europe, where many species are dependent on low-yielding high nature value farmland threatened by both intensification and abandonment. In the first multi-taxon population-level test of land-sparing theory in Europe, we quantified how population densities of 175 bird and sedge species varied with farm yield across 26 squares (each with an area of 1 km2) in eastern Poland. We discovered that, as in previous studies elsewhere, simple land sparing, with only natural habitats on spared land, markedly out-performed land sharing in its effect on region-wide projected population sizes. However, a novel 'three-compartment' land-sparing approach, in which about one-third of spared land is assigned to very low-yield agriculture and the remainder to natural habitats, resulted in least-reduced projected future populations for more species. Implementing the three-compartment model would require significant reorganization of current subsidy regimes, but would mean high-yield farming could release sufficient land for species dependent on both natural and high nature value farmland to persist.Supported by a NERC CASE studentship to C.F

The biodiversity intactness index may underestimate losses.

The Biodiversity Intactness Index (BII) is a high-profile metric of an area’s average abundance of wild species relative to that in pre-modern times1 or in primary vegetation under current climatic conditions2. It has been endorsed by the Group on Earth Observations of the Biodiversity Observation Network, adopted by the Intergovernmental Platform on Biodiversity and Ecosystem Services as a "core" indicator of progress towards the Convention on Biological Diversity’s Aichi targets 12 and 14, and accepted by the Biodiversity Indicators Partnership as an indicator for Aichi target 5. We strongly support development of spatially-explicit indicators such as the BII, which can be used to prioritise areas for conservation interventions. However, it is important that the metric is as robust as possible, and we have noticed several unusual features of the BII that concern us

Order of meals at the counter and distance between options affect student cafeteria vegetarian sales

Altering the order in which meals are presented at cafeteria counters has been proposed as a way of lowering meat consumption, but remains largely untested. To address this, we undertook two experimental studies involving 105,143 meal selections in the cafeterias of a British university. Placing vegetarian options first on the counter consistently increased their sales when choices were widely separated (>1.5 m; vegetarian sales as a percentage of total meal sales increased by 4.6 and 6.2 percentage points) but there was no evidence of an effect when the options were close together (<1.0 m). This suggests that order effects depend on the physical distance between options.This work was supported by E.E.G.’s NERC studentship grant number NE/L002507/1 and A.B.’s Royal Society Wolfson Research Merit awar

Reducing the land use of EU pork production: where there's swill, there's a way.

Livestock production occupies approximately 75% of agricultural land, consumes 35% of the world's grain, and produces 14.5% of anthropogenic greenhouse gas emissions. With demand for meat and dairy products forecast to increase 60% by 2050, there is a pressing need to reduce the footprint of livestock farming. Food wastes have a long history as a source of environmentally benign animal feed, but their inclusion in feed is currently banned in the EU because of disease control concerns. A number of East Asian states have in the last 20 years, however, introduced regulated, centralised systems for safely recycling food wastes into animal feed. This study quantifies the land use savings that could be realised by changing EU legislation to promote the use of food wastes as animal feed and reviews the policy, public, and industry barriers to the use of food waste as feed. Our results suggest that the application of existing technologies could reduce the land use of EU pork (20% of world production) by one fifth, potentially saving 1.8 million hectares of agricultural land. While swill presents a low-cost, low-impact animal feed, widespread adoption would require efforts to address consumer and farmer concerns over food safety and disease control.E.K.H.J.zE is funded by BBSRC grant BB/J014540/1.This is the final version of the article. It was first available from Elsevier via http://dx.doi.org/10.1016/j.foodpol.2015.11.00

Crop expansion and conservation priorities in tropical countries

Expansion of cropland in tropical countries is one of the principal causes of biodiversity loss, and threatens to undermine progress towards meeting the Aichi Biodiversity Targets. To understand this threat better, we analysed data on crop distribution and expansion in 128 tropical countries, assessed changes in area of the main crops and mapped overlaps between conservation priorities and cultivation potential. Rice was the single crop grown over the largest area, especially in tropical forest biomes. Cropland in tropical countries expanded by c. 48,000 km2 per year from 1999–2008. The countries which added the greatest area of new cropland were Nigeria, Indonesia, Ethiopia, Sudan and Brazil. Soybeans and maize are the crops which expanded most in absolute area. Other crops with large increases included rice, sorghum, oil palm, beans, sugar cane, cow peas, wheat and cassava. Areas of high cultivation potential—while bearing in mind that political and socio-economic conditions can be as influential as biophysical ones—may be vulnerable to conversion in the future. These include some priority areas for biodiversity conservation in tropical countries (e.g., Frontier Forests and High Biodiversity Wilderness Areas), which have previously been identified as having ‘low vulnerability’, in particular in central Africa and northern Australia. There are also many other smaller areas which are important for biodiversity and which have high cultivation potential (e.g., in the fringes of the Amazon basin, in the Paraguayan Chaco, and in the savanna woodlands of the Sahel and East Africa). We highlight the urgent need for more effective sustainability standards and policies addressing both production and consumption of tropical commodities, including robust land-use planning in agricultural frontiers, establishment of new protected areas or REDD+ projects in places agriculture has not yet reached, and reduction or elimination of incentives for land-demanding bioenergy feedstock

Discrepancies between two long-term dietary datasets in the United Kingdom

Background: Studying dietary trends can help monitor progress towards healthier and more sustainable diets but longitudinal data are often confounded by lack of standardized methods. Two main data sources are used for longitudinal analysis of diets: food balance sheets on food supply (FBS) and household budget surveys on food purchased (HBS). Methods: We used UK longitudinal dietary data on food supply, provided by the Food and Agriculture Organisation (FAO) (FAO-FBS, 1961-2018), and food purchases, provided by the Department for Environment, Food and Rural Affairs (Defra) (Defra-HBS, 1942-2018). We assessed how trends in dietary change per capita compared between FAO-FBS and Defra-HBS for calories, meat and fish, nuts and pulses, and dairy, and how disparities have changed over time. Results: Estimates made by FAO-FBS were significantly higher (p<0.001) than Defra-HBS for calorie intake and all food types, except nuts and pulses which were significantly lower (p<0.001). These differences are partly due to inclusion of retail waste in FAO-FBS data and under-reporting in Defra- HBS data. The disparities between the two datasets increased over time for calories, meat and dairy; did not change for fish; and decreased for nuts and pulses. Between 1961 and 2018, both FAO-FBS and Defra-FBS showed an increase in meat intake (+23.4% and +1.4%, respectively) and a decrease in fish (-7.1% and -3.2%, respectively). Temporal trends did not agree between the two datasets for dairy, calories, and nuts and pulses. Conclusions: Our finding raises questions over the robustness of both data sources for monitoring UK dietary change, especially when used for evidence-based decision making around health, climate change and sustainability

Support amongst UK pig farmers and agricultural stakeholders for the use of food losses in animal feed.

While food losses (foods which were intended for human consumption, but which ultimately are not directly eaten by people) have been included in animal feed for millennia, the practice is all but banned in the European Union. Amid recent calls to promote a circular economy, we conducted a survey of pig farmers (n = 82) and other agricultural stakeholders (n = 81) at a UK agricultural trade fair on their attitudes toward the use of food losses in pig feed, and the potential relegalisation of swill (the use of cooked food losses as feed). While most respondents found the use of feeds containing animal by-products or with the potential for intra-species recycling (i.e. pigs eating pork products) to be less acceptable than feeds without, we found strong support (>75%) for the relegalisation of swill among both pig farmers and other stakeholders. We fit multi-hierarchical Bayesian models to understand people's position on the relegalisation of swill, finding that respondents who were concerned about disease control and the perception of the pork industry supported relegalisation less, while people who were concerned with farm financial performance and efficiency or who thought that swill would benefit the environment and reduce trade-deficits, were more supportive. Our results provide a baseline estimate of support amongst the large-scale pig industry for the relegalisation of swill, and suggest that proponents for its relegalisation must address concerns about disease control and the consumer acceptance of swill-fed pork

Roads as a contributor to landscape-scale variation in bird communities.

Roads and their traffic can affect wildlife over large areas and, in regions with dense road networks, may influence a high proportion of the ecological landscape. We assess the abundance of 75 bird species in relation to roads across Great Britain. Of these, 77% vary significantly in abundance with increasing road exposure, just over half negatively so. The effect distances of these negative associations average 700 m from a road, covering over 70% of Great Britain and over 40% of the total area of terrestrial protected sites. Species with smaller national populations generally have lower relative abundance with increasing road exposure, whereas the opposite is true for more common species. Smaller-bodied and migratory species are also more negatively associated with road exposure. By creating environmental conditions that benefit generally common species at the expense of others, road networks may echo other anthropogenic disturbances in bringing about large-scale simplification of avian communities

How imperfect can land sparing be before land sharing is more favourable for wild species?

Two solutions, at opposite ends of a continuum, have been proposed to limit negative impacts of human agricultural demand on biodiversity. Under land sharing, farmed landscapes are made as beneficial to wild species as possible, usually at the cost of lower yields. Under land sparing, yields are maximised and land not needed for farming is spared for nature. Multiple empirical studies have concluded that land-sparing strategies would be the least detrimental to wild species, provided the land not needed for agriculture is actually spared for nature. However, the possibility of imperfections in the delivery of land sparing has not been comprehensively considered. Land sparing can be imperfect in two main ways: land not required for food production may not be used for conservation (incomplete area sparing), and habitat spared may be of lower quality than that assessed in surveys (lower habitat quality sparing). Here we use published data relating population density to landscape-level yield for birds and trees in Ghana (167 and 220 species respectively) and India (174 birds, 40 trees) to assess effects of imperfect land sparing on region-wide population sizes and hence population viabilities. We find that incomplete area and lower habitat quality imperfections both reduce the benefits of a land-sparing strategy. However, sparing still outperforms sharing whenever >= 28% of land that could be spared is devoted to conservation, or the quality of land spared is >= 29% of the value of that surveyed. Thresholds are even lower under alternative assumptions of how population viability relates to population size and for species with small global ranges, and remain low even when both imperfections co-occur. Comparison of these thresholds with empirical data on the likely real-world performance of land sparing suggests that reducing imperfections in its delivery would be highly beneficial. Nevertheless, given plausible relationships between population size and population viability, land sparing outperforms land sharing despite its imperfections. Policy implications. Our results confirm that real-world difficulties in implementing land sparing will have significant impacts on biodiversity. They also underscore the need for strategies which explicitly link yield increases to setting land aside for conservation, and for adoption of best practices when spared land requires restoration. However, land-sparing approaches to meeting human agricultural demand remain the least detrimental to biodiversity, even with current imperfections in implementation